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I have a problem for my next project. I want to buy a Minitel (a French terminal, ancestor of PC and Internet). Once I have it, I want to remove the old screen and everything that is inside then put a new screen and a little PC box inside it. This will be the easy part.

The hardest part is that I want to keep using the old keyboard, so I think I should find a way to put electricity into it and solder some wire to get whatever comes out of it.

This is where you guys can help me: What should I use to get the outputs of the old keyboard and code something to translate them in order to get a USB input for the new PC?

Connection from a Minitel to a PC

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    Same comment as you got in EE.SE: you need to figure out the electrical interface and protocol used by the old keyboard. Only after that you can start to figure out with what it can be interfaced. Do you have any information, schematics or service manual that could have this info?
    – Justme
    Dec 1, 2022 at 9:44
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    Standard pedantry: the internet, which began in the 1960s, is not a descendant of the Minitel, which first came to market in 1982. Neither is the 1981 IBM PC.
    – Tommy
    Dec 1, 2022 at 14:30
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    Are you sure you want to get rid of the crt screen? Shame... There are lots of tutorials for using minitels as terminals. Of course, graphics capabilities are more than limited, but that's the beauty of it...
    – dim
    Dec 1, 2022 at 18:28
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    @user20439316 are you aware that the web is not the internet, and is not even the first web-style interface on the internet?
    – Tommy
    Dec 2, 2022 at 12:26
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    I guess the correct historical framing would be that Minitel was the French take on Compuserve, Prestel, etc. As per Wikipedia’s article on Videotex in general: “Meanwhile … the French government was determined to catch up on a perceived falling behind in its computer and communications facilities”. Although hugely significant for the scale of its deployment, in technological terms Minitel followed, it didn’t lead.
    – Tommy
    Dec 2, 2022 at 12:47

1 Answer 1

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This Instructables project by Gautchh shows how to handle the keyboard. The keyboard uses a simple matrix with a 17-wire output; pressing a key connects two of the wires. In Gautchh’s project, the matrix is decoded using an Arduino, which emulates a USB HID keyboard. The matrix is as follows:

      //  5   4   3   2  15  14  13   9
/* 6  */{'c','D','Q','5','r','l',' ',' '},
/* 7  */{'L','F','Y','A',',','r','s',' '},
/* 17 */{'K','G','Z','T','.','a','c',' '},
/* 16 */{'J','H','E','R','"',' ','g',' '},
/* 12 */{'V','C',';','U','e','r','s',' '},
/* 11 */{'B','X','-','I','*','4','7','1'},
/* 10 */{'P','W',':','N','O','5','8','2'},
/* 8  */{'M',' ','?','O','#','9','6','3'}};

An Arduino program is provided to handle the conversion for you. You still need to connect the Arduino to the keyboard of course!

The above matrix is partial, and corresponds to that used in the Arduino project; another site (in French) gives a complete matrix for an Alcatel Telic Minitel 1B:

15 14 13 12 5 4 3 2
16 Correction Annulation Shift
11 T E R Y ; - : ?
10 G D F H * 7 4 1
9 . Esc , ' Suite Retour Envoi Répétition
8 B C V N 0 8 5 2
7 Guide Z A Sommaire U I O P
6 Fnct S Q Ctrl J K L M
1 Connexion / Fin X W Espace # 9 6 3

The two matrices don’t match, so it’s possible you’ll have to figure out the matrix for whatever keyboard you have.

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  • Why are there two Cs? At 6/5 and 12/4? There are also two Os, at 8/2 and 10/15, many spaces, and maybe other duplicates. Why are the columns and rows not in order? I feel like this answer needs more explanation about what we're looking at here. It does not look like "a simple matrix". Dec 2, 2022 at 9:20
  • @OmarL: there is a lowercase and uppercase 'c', of the two capital 'O's one should probably be a '0' (zero), and the many spaces are likely unused combinations (except for the one 'real' space)
    – Pelle
    Dec 2, 2022 at 13:36
  • @Pelle so what are both upper and lower case doing in a keyboard matrix? Usually the matrix identifies a key, not the glyph. Also there are missing keys such as cursor movement, Ctrl, Shift, etc. And where are "Connexion Fin", "Sommaire", "Annullation", etc, are they ignored or mapped to some PC specific thing like Insert or prtscr? So the plot thickens... Dec 2, 2022 at 13:54
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    @OmarL looking at the code, I guess the lowercase codes are the 'command-keys', the code maps 'r' to KEY_BACKSPACE. The rest seems to be not implemented.
    – Pelle
    Dec 2, 2022 at 14:06

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